X-linked agammaglobulinemia (XLA) is a humoral primary immunodeficiency in which affected patients have very low levels of peripheral B cells and a profound deficiency of all immunoglobulin isotypes. Mutations in the gene encoding for Bruton's tyrosine kinase (Btk) are responsible for most of the gammaglobulinemia.

We tend to investigate the gene mutation and clinical features of Chinese X-linked agammaglobulinemia (XLA) patients, and also examined the relationship between specific Btk gene mutations and severity of clinical presentation.

Inclusion Criteria:

• Clinical diagnosis of XLA A.male patients with less than 2% CD19-positive B cells; B.recurrent bacterial infection; C.decreased or absent immunoglobulins in serum

Exclusion Criteria for all groups:

• Presence of other primary immunodeficiency syndromes that do not meet the clinical and laboratory criteria for XLA

XLA patients